Question

ch 3* the length of human pregnancies from conception to birth varies according to a distribution that is approximately normal with mean 266 days and standard deviation 16 days. about 68% of all pregnancies last between

○ 218 and 314 days.

○ 250 and 282 days.

○ 234 and 298 days.

Explanation:

Step1: Recall the empirical rule for normal distribution

For a normal - distributed data, about 68% of the data lies within 1 standard deviation of the mean.

Step2: Calculate the lower limit

The lower limit is $\text{mean}-\text{standard deviation}$. Given mean $\mu = 266$ days and standard deviation $\sigma=16$ days. So, the lower limit is $266 - 16=250$ days.

Step3: Calculate the upper limit

The upper limit is $\text{mean}+\text{standard deviation}$. So, the upper limit is $266 + 16 = 282$ days.

Answer:

250 and 282 days.